package com.gmh.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.gmh.utils.RedisConstants.*;

@Slf4j
@Component
public class CacheClient {
    private StringRedisTemplate stringRedisTemplate;

    public CacheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit) {
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
    }

    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit) {
        // 设置逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value), time, unit);
        // 写入redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    public <R , ID> R queryWithPassThrough(String keyPrefix, ID id, Class<R> type, Function<ID, R> dbFallback, Long time, TimeUnit unit){   //缓存穿透
        //1.从redis查询id缓存
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在redis缓存
        if (StrUtil.isNotBlank(json)){
            //存在，直接返回
            return JSONUtil.toBean(json, type);
        }
        //判断redis命中是否为空值
        if(json != null)
        {
            return null;
        }
        //4.不存在，根据id查询数据库
        R r = dbFallback.apply(id);
        //5.数据库不存在，返回错误
        if (r == null){
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //6.存在，写入redis
        this.set(key, r, time, unit);
        return r;
    }
    private static final ExecutorService CACHE_REDIS_EXECUTOR = Executors.newFixedThreadPool(10);
    public <R> R queryLogicalExpire(String keyPrefix,Long id, Class<R> type, Function<Long, R> dbFallback, Long time, TimeUnit unit){
        //1.从redis查询id缓存
        String key = keyPrefix + id;
        String json = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在redis缓存
        if (StrUtil.isBlank(json)){
            //不存在，查询数据库并添加redis缓存
            //自己加的
            R r = dbFallback.apply(id);
            if (r == null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            this.set(key, r, time, unit);
            this.setWithLogicalExpire(key, r, time, unit);
            return r;
        }
        //命中
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime(); // 获取过期时间
        //3.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //未过期，直接返回
            return r;
        }
        //4.过期，根据id查询数据库
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock =tryLock(lockKey);
        if (isLock){
            CACHE_REDIS_EXECUTOR.submit(() -> {
                try {
                    // 查询数据库
                    R r1 = dbFallback.apply(id);
                    // 写入redis
                    this.setWithLogicalExpire(key, r1, time, unit);
                }catch(Exception e) {
                    throw new RuntimeException();
                }finally{
                    //6.释放锁
                    unLock(lockKey);
                }
            });
        }
        //7.返回
        return r;
    }

    private boolean tryLock (String key) {
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }

    private void unLock (String key) {
        stringRedisTemplate.delete(key);
    }
}
